#include <iostream>

class Sales_data {
public:
	Sales_data(std::string s, unsigned cnt, double price):
		bookNo(s), units_sold(cnt), revenue(cnt*price) {  }
	Sales_data(): Sales_data("", 0, 0) {  }
	Sales_data(std::string s): Sales_data(s, 0, 0) {  }
	// Sales_data(std::istream &is): Sales_data() { read(is, *this); }
private:
	std::string bookNo;
	unsigned units_sold = 0;
	double revenue = 0.0;
};

int main(void)
{
	return 0;
}
